Use the pre-build SharinPix Album with Chatter Feed
SharinPix allows you to use chatter on specific images with the built-in component, SharinPix Album with Chatter.
The SharinPix Album with Chatter component was previously named SharinPix with Chatter.
Edit the page in lightning view.
Once done, search for the SharinPix Album with Chatter component and drag and drop the it on the preview page. Click save when done.
You can now go back onto your page and start using the Chatter.
Click on the image you want to start a discussion on, and click on the Start a discussion button on the right side of the component.
Chatter can also be used on specific Annotations by click on the annotation, then starting a discussion.